Electrical Contour fans to a toggle switch, what do I need?

Bosch 75A.
This will control the fan automatically via the temperature switch installed in the thermostat housing.
If no A/C, eliminate the relay on the right & the wire to the fan clutch.

How much of the fan system did you get? If you got the wire harness that connects the fans in a single plug at top of shroud, one wire will give you low speed of both fans, one wire will give you high speed. If you wire the toggles to trigger one relay each, then the output 12V power from each can be wired to each of the two factory wires at that connector. Then you have high and low speed fans on 2 toggles.

If you have or planning to use some of the Contour wiring, see post 1-3 here...

I am not familiar with the harness from LMR. I just went to their site and checked what you get. It looks to me that you get 2 pigtails, one for each motor. On the Contour they are wired together (both come on, either high speed or low speed). Low speed goes through the thermo resistor included on the fan (lower driver side of shroud), high speed gets full 12V power. Basically the most simple installation is a 70 A relay (factory Contour uses 70 A for low and another 70 A for high speed) that is actuated by your toggle. Wire the two motor positives together and grounds together. You will have high speed fan anytime you throw the toggle. Simple and basic.

Power wire from battery to fuse, fuse to relay and relay to fans should be the larger gauge. Power from toggle to switching side of relay and ground can be 18 gauge as Blown88GT's diagram shows.

Enjoy

Blown88GT said:

Bosch 75A.
This will control the fan automatically via the temperature switch installed in the thermostat housing.
If no A/C, eliminate the relay on the right & the wire to the fan clutch.

Click to expand...

This is the best input you have gotten so far. Take it and run with it,

If you don't have a high current alternator, you can forget about using an electric fan. The stock 65 amp alternator on 86-93 Mustangs isn't big enough to run the fan and the rest of the car. If you have a 94 or later Mustang, the stock 3g alternator should be fine if it is working correctly.

Switching a fan on and off manually is a bad idea. Too many guys have been distracted (hot girl kissing on their neck, too much to drink, dog tired and not thinking clearly) and cooked things because they forgot to flip the switch. An equal number have forgotten to turn the switch off for the same reasons and run down their battery.

The best fan controller available today is a DC Control unit. www.dccontrol.com. Cost is about $???. Be prepared to wait 4 weeks or more to receive your controller once you have sent in your payment. The controllers are custom made in small lots and lead times can stretch out.

Next best is a SPAL controller - $70-$170 See http://www.spalusa.com/store/Main.aspx?html=pwmv3. eBay will have the controllers for a bargain price: do a Google search and see what you find.

At the bottom are the Hayden or Imperial controllers available through Advance Discount Auto Parts and AutoZone. The non adjustable one is about $30 ( Hayden 226206) and the adjustable one is about $60 (Hayden 226204). I recommend you do a Google search on Hayden and the part number for more info.

Do not use a simple on/off switch without using a relay. The high current load can burn up the typical cheap automotive switch very quickly. The fan draws 30 or more amps and you need to use #10 or #8 wire on the fan power and ground wiring.


Alternate placement for a temp gauge sender or temp switch/temp sensor for an electric fan. Use the heater feed that comes off the intake manifold. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. Be sure to use the same water feed line as the ECT sensor. That way you will get the most accurate temp readings.

Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.

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